Slate with Quartz Vein

Physical Properties

Mohs hardness: 2.5-4 for slate, 7 for vein; Color: Dark grey to charcoal with a white/tan vein; Luster: Dull to pearly; Structure: Foliated with slaty cleavage; SG: 2.7-2.8

Formation & Geological History

Formed through the low-grade regional metamorphism of shale or mudstone under relatively low pressure and temperature. The quartz vein likely formed later through hydrothermal activity where mineral-rich water filled fractures.

Uses & Applications

Slate is used for roofing, flooring, billiard tables, and blackboards. Specimens with aesthetic quartz veins are used for garden decoration or amateur mineral collecting.

Geological Facts

Slate can easily be split into thin, flat sheets. The presence of a vein suggests a tectonic event occurred after the rock consolidated, cracking the rock and allowing fluids to deposit minerals.

Field Identification & Locations

Identify by its fine-grained texture, dark color, and ability to split into plates. Look for 'slaty cleavage.' Found in mountainous regions or areas with ancient seafloor deposits that underwent metamorphism.

Identified on: 5/19/2026

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